package yukicoder211;
import java.util.Scanner;
public class Main {
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		int k=sc.nextInt();
		int[] p={2,3,5,7,11,13};
		int[] c={4,6,8,9,10,12};
		double count=0;
		for(int i=0;i<6;i++){
			for(int j=0;j<6;j++){
				if(k==p[i]*c[j])
					count++;
			}
		}
		System.out.println(count/(double)36);
	}
}